New Designs for Friendly Visual Cryptography Scheme

NSC101-2221-E-032-047[[abstract]]Different from conventional cryptography, visual cryptography is an image cryptographic technique proposed by Naor and Shamir. It encodes a secret image into n pieces of noise-like shares. When k or more than k pieces of shares are gathered from participants, human visual system will disclose the secret image on the stacked image easily. Neither complicated mathematical computation nor any knowledge of cryptography are needed are the main advantages of visual cryptography. In this paper, we propose a new design for friendly visual cryptography scheme. The secret will be hiding into two meaningful shares. The black-appearing ratio in each block of the shares for the corresponding black (rep. white) secret pixel is the same. Therefore, it is impossible for one to disclose any information related to the secret image on each share, which achieves the goal of improving security. When shares are superimposed, the contours of the cover image will disappear on the stacked image, which will only reveal the secret image. According to our experimental results, the contrasts of the shares or the stacked images are good which can reveal the contents of the cover images and the secret image clearly.[[notice]]補正完畢[[journaltype]]國外[[ispeerreviewed]]Y[[booktype]]紙本[[countrycodes]]SG

Embedded Extended Visual Cryptography Schemes

Visual cryptography scheme (VCS) is a kind of secret sharing scheme which allows the encoding of a secret image into n shares that distributed to n participants. The beauty of such scheme is that a set of qualified participants is able to recover the secret image without any cryptographic knowledge and computation devices. Extended visual cryptography scheme (EVCS) is a kind of VCS which consists of meaningful shares (compared to the random shares of traditional VCS). In this paper, we propose a construction of EVCS which is realized by embedding random shares into meaningful covering shares, and we call it the embedded extended visual cryptography scheme (embedded EVCS). Experimental results compare some of the well-known EVCS\u27s proposed in recent years systematically, and show that the proposed embedded EVCS has competitive visual quality compared with many of the well-known EVCS\u27s in the literature. Besides, it has many specific advantages against these well-known EVCS\u27s respectively

Visual cryptography with cheating shares

Visual cryptography is a technique that applies the human visual system to decode encrypted information, such as text, image and number, without any sophisticated devices and computing capabilities. Therefore, compared with the traditional cryptography, it is apparent that it saves a large amount of time and money on devices and computations. Also, visual cryptography provides the convenience for humans to carry out decryption with a portal card which is significant to the business application. In the past decade, visual cryptography has been thoroughly researched not only on its contrast and subpixel expansion, but also on its applications. The main contribution of this thesis is the security of visual cryptography related to the dishonest shareholders. This is the first known work concerning this variety of potentially secure problem. In the previous papers, the shareholders are inherently honest. However, in the real world, it is impossible to guarantee that every shareholder would be honest forever(e.g., because of the interest of business or military, some shareholders might change to be the traitors). Therefore, a new method based on visual authentication[16] is proposed and the improvement is also made. In this thesis, we also review the previous papers on different fields of the visual cryptography

Secret Sharing in Visual Cryptography

This thesis examines techniques for recursive hiding scheme for 3 out of 5 secret sharing and a probabilistic 2 out of 3 secret sharing scheme for gray scale images. In recursive hiding of secrets several messages can be hidden in one of the shares of the original secret image. The images that are to be hidden are taken according to their sizes from smaller to the largest. The first small secret image is divided into five different shares using visual cryptography. These shares are placed in the next level to create the shares of larger secret information. The shares at each consecutive level are distributed so that no one has access to all the shares of the smaller images, unless at least three participants come together to reveal the secret information, resulting in 3 out of 5 scheme. In the proposed protocol for gray scale images, the quality of the image is perfect when it is reconstructed for the construction of the final image based on the binary OR operation.Computer Science Departmen

Improvement Of Hybrid Digital Image Watermarking Schemes Based On Svd In Wavelet Transform Domain

Digital image watermarking techniques have enabled imperceptible information in images to be hidden to ensure the information can be extracted later from those images. Robustness, imperceptibility, capacity and security are the most important requirements of any watermarking scheme. Recently, hybrid Singular Value Decomposition (SVD)- based watermarking schemes in the wavelet domain have significantly gained a lot of attention. The aim of this study is to develop hybrid digital image watermarking schemes by combining the properties of SVD and the chosen wavelet transforms to achieve high robustness and imperceptibility, as well as maintaining the trade-off between robustness, imperceptibility and capacity. The security issue due to the false positive problem (FPP) that may be occurring in most of SVD-based watermarking schemes, has been covered and addressed. This study proposes five hybrid robust SVD-based image watermarking schemes in the wavelet domain. In the first scheme, a grey image watermark is embedded directly into the singular values (S) of each redundant discrete wavelet transform transform (RDWT) sub-band of the host image. The scheme is named RDWT-SVD. The second proposed scheme, namely IWT-SVD-AT, utilised the integer wavelet transform (IWT) instead of RDWT due to its properties. The watermark is scrambled using Arnold Transform (AT) before being embedded into the S of each IWT sub-band host. Despite the impressive results by the first and the second schemes, they were vulnerable to the FPP. Thus, they have failed to resolve the rightful ownership. In the third scheme, a hybrid IWT-SVD scheme is proposed with a novel Digital Signature (DS)-based authentication mechanism to solve the FPP. The scheme outperforms the previous schemes in terms of robustness, capacity, security, computation time and attains high imperceptibility. In the remaining two proposed schemes; the fourth and fifth schemes, the FPP is totally avoided using new different embedding strategies. In the fourth scheme namely IWT-SVD-MOACO, the singular vector U of the watermark is embedded into the S of IWT LL sub-band. Multi-objective ant colony optimisation (MOACO) is used to find the optimal multiple zooming/scaling factor (MZF) instead of the single scaling factor (SSF) to achieve the optimal trade-off between imperceptibility and robustness. Finally, a hybrid SVD block-based scheme namely DWT-SVD-HVS using discrete wavelet transform (DWT) is developed. A binary watermark is embedded into a number of blocks which is selected based on some human visual system (HVS) criterion. The scheme shows a high imperceptibility and good robustness. Finally, all the proposed schemes are evaluated with different colour images and had been shown a successful applicability with colour images

Application and Theory of Multimedia Signal Processing Using Machine Learning or Advanced Methods

This Special Issue is a book composed by collecting documents published through peer review on the research of various advanced technologies related to applications and theories of signal processing for multimedia systems using ML or advanced methods. Multimedia signals include image, video, audio, character recognition and optimization of communication channels for networks. The specific contents included in this book are data hiding, encryption, object detection, image classification, and character recognition. Academics and colleagues who are interested in these topics will find it interesting to read

Privacy-preserving information hiding and its applications

The phenomenal advances in cloud computing technology have raised concerns about data privacy. Aided by the modern cryptographic techniques such as homomorphic encryption, it has become possible to carry out computations in the encrypted domain and process data without compromising information privacy. In this thesis, we study various classes of privacy-preserving information hiding schemes and their real-world applications for cyber security, cloud computing, Internet of things, etc. Data breach is recognised as one of the most dreadful cyber security threats in which private data is copied, transmitted, viewed, stolen or used by unauthorised parties. Although encryption can obfuscate private information against unauthorised viewing, it may not stop data from illegitimate exportation. Privacy-preserving Information hiding can serve as a potential solution to this issue in such a manner that a permission code is embedded into the encrypted data and can be detected when transmissions occur. Digital watermarking is a technique that has been used for a wide range of intriguing applications such as data authentication and ownership identification. However, some of the algorithms are proprietary intellectual properties and thus the availability to the general public is rather limited. A possible solution is to outsource the task of watermarking to an authorised cloud service provider, that has legitimate right to execute the algorithms as well as high computational capacity. Privacypreserving Information hiding is well suited to this scenario since it is operated in the encrypted domain and hence prevents private data from being collected by the cloud. Internet of things is a promising technology to healthcare industry. A common framework consists of wearable equipments for monitoring the health status of an individual, a local gateway device for aggregating the data, and a cloud server for storing and analysing the data. However, there are risks that an adversary may attempt to eavesdrop the wireless communication, attack the gateway device or even access to the cloud server. Hence, it is desirable to produce and encrypt the data simultaneously and incorporate secret sharing schemes to realise access control. Privacy-preserving secret sharing is a novel research for fulfilling this function. In summary, this thesis presents novel schemes and algorithms, including: • two privacy-preserving reversible information hiding schemes based upon symmetric cryptography using arithmetic of quadratic residues and lexicographic permutations, respectively. • two privacy-preserving reversible information hiding schemes based upon asymmetric cryptography using multiplicative and additive privacy homomorphisms, respectively. • four predictive models for assisting the removal of distortions inflicted by information hiding based respectively upon projection theorem, image gradient, total variation denoising, and Bayesian inference. • three privacy-preserving secret sharing algorithms with different levels of generality